Initial Insight into the 26 June 2015 Kansas City Severe Mesoscale Convective System

Nocturnal mesoscale convective systems (MCSs) are known to produce a wide array of hazards from flash flooding to damaging surface winds. While the mechanisms that lead to flooding are becoming increasingly understood, the forces that drive severe surface winds in nocturnal systems remain unclear. Are such systems elevated or surface-based? How are they maintained? A severe nocturnal MCS developed west of the Kansas City, Missouri metropolitan area on 26 June 2015 and progressed southeastward. The system was initially thought to be elevated, but it eventually developed two distinct bowing segments that produced wide swaths of damaging winds over the aforementioned urban area. As part of the 2015 Plains Elevated Convection At Night (PECAN) field project, data were collected from the system as it evolved into a severe thunderstorm complex.

Interestingly, a simulation of this system in an idealized, horizontally homogeneous model evolved similarly to the observed MCS. Damaging winds were confined to a wide swath associated with a bow echo in simulated reflectivity. Analyses of near-surface passive tracers suggested that while the convective system was originally elevated, the aforementioned bowing segment of the MCS became surface-based while producing damaging winds. We will present analyses of the processes associated with the simulated evolution toward a surface-based severe wind-producing system.